He's not really talking about where you write. He's just talking about changing expectations for writing. They're independent ideas.
Also, it's a canard that Medium gives you a larger audience. Even if everybody is there, everybody isn't going to be reading what you wrote.
Bottomline: smaller targeted audience > larger unfocused audience. Step 1: write about what you find interesting. Step 2: find your homies and show it to them. They're hard to find, but they aren't captive to any single gatekeeper.
Also, it's a canard that Medium gives you a larger audience. Even if everybody is there, everybody isn't going to be reading what you wrote.
Bottomline: smaller targeted audience > larger unfocused audience. Step 1: write about what you find interesting. Step 2: find your homies and show it to them. They're hard to find, but they aren't captive to any single gatekeeper.